Rally organizer Miguel Lopez said volunteers were cleaning up the area around 10:30 p.m. Thursday night when a man went through the park, tearing up trash bags. When volunteers confronted him, Lopez said the man threatened them with a knife.

Organizers came back Friday to finish cleaning, he said. Their permit expires at 11:59 p.m., city parks officials said.

Early Friday, city workers took photos of the trash piles as people walking to their offices picked their way through the mess, some stopping to stare and take their own pictures. A worker mentioned that the park had been clean the night before.

Several thousand people spent Thursday in Civic Center for the annual 4/20 rally. The event included vendors, food trucks, the 4:20 p.m. marijuana smoke in and a 2 Chainz concert that ended around 6 p.m. The festival was scheduled to end at 8 p.m., organizers said.

Dawnarie Brook’s was out cleaning up the trash Friday morning. She had gone to the 4/20 rally yesterday and said the park was clean — although “it wasn’t immaculate,” she said, when she was leaving at about 8 p.m.

She left the Samaritan House Homeless Shelter this morning around 6:30 a.m. and was shocked when she reached Civic Center. She’s been cleaning at least one of the large garbage piles since, collecting trash into boxes because the city trash can was lying on its side. A passerby heard her talking about the situation and stopped to help stand the heavy trash can back up.

Brook’s said she was going to keep cleaning until that pile was gone, but would have to stop at that point because her back was in too much pain. For her, it was especially upsetting to see all of the recyclables that have been strewn around and rained on.